• Tiada Hasil Ditemukan

I wish to express my profound gratitude to God Almighty for His protection from the beginning of my programme till now

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SYNTHESIS, CHARACTERIZATION AND ACTIVITY OF MIXED METAL OXIDE (Mg, Zn, Al) CATALYSTS FOR TRANSESTERIFICATION OF

WASTE COOKING PALM OIL, EDIBLE AND NON-EDIBLE OILS

OLUTOYE, MOSES ADEREMI

UNIVERSITI SAINS MALAYSIA 2012

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SYNTHESIS, CHARACTERIZATION AND ACTIVITY OF MIXED METAL OXIDE (Mg, Zn, Al) CATALYSTS FOR TRANSESTERIFICATION OF

WASTE COOKING PALM OIL, EDIBLE AND NON-EDIBLE OILS

by

OLUTOYE, MOSES ADEREMI

Thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy

APRIL 2012

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iii

ACKNOWLEDGEMENT

I will start with these few words: Who is this? Great and Mighty One;

Who rules the earth; Who sets above; HE is my GOD and HE IS GREAT. I wish to express my profound gratitude to God Almighty for His protection from the beginning of my programme till now. May His glorious name be praised forever- Amen. I would like to express my special appreciation to my supervisor, Professor Bassim H. Hameed for his constant guidance and great inspiration throughout the duration of my research programme. It’s a great opportunity to have worked under his supervision. I would like to acknowledge gratefully my co-supervisor Professor Abdul Latif Ahmad for his encouragement through the research work.

I would like to extend my heartiest appreciation to Institute of Postgraduate School, Universiti Sains Malaysia for the contribution made to support the research through the Postgraduate Research Grant Scheme (PGRS) No. 8042031 and Ministry of Science, Technology and Innovation (MOSTI) SF0207. My sincere thanks go to all administrative and technical staff in the School of Chemical Engineering for their valuable help and co-operation. The support of top hierarchy in the School, most especially the Dean, Professor Azlina Bt. Harun @ Kamaruddin, Deputy Dean Research, Assoc. Prof. Dr. Lee Keat Teong et al. is highly appreciated. Dr.

Suzylawati Ismail is highly appreciated for kind assistance in the abstract translation to Bahasa Malaysia.

I really appreciate the sacrifice of my lovely wife and adorable children (Miracle Omowumi, Israel Gift Ifeoluwa, Deborah Abiodun Oluwaseyi Praise and Ephraim Boluwatife Oluwatobi Oluwatimilehin). They have been the source of my inspiration and motivation. I miss them for more than 3 years. God gave her the infinite strength to play the role of both father and mother even in my absence for 3 years. She

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ensured the welfare of the children is fulfilled so that I can concentrate fully on my PhD abroad. Thank you my Dear Faith Olunike Ronke (FOR Olutoye). God will surely reward her love, care, prayers and concern always.

I am indebted to my colleagues at the Federal University of Technology (FUT), Minna, beginning with Prof. K. R. Onifade of Chemical Engineering Department, Federal University of Technology (FUT), Minna, Nigeria. Professor Folorunso Aberuagba, Professor J. O. Odigure, present and past Head of Department, Chemical Engineering, present and past Dean School of Engineering and Engineering Technology (SEET), especially Professor F.O. Akinbode. In the same vein, I really appreciate the following for facilitating my release for the PhD programme. They are the top hierarchy in FUT, Minna administration, Mr. M. D. Usman, the Registrar, (FUT), Minna, Nigeria, Professor Lamai, Dean of Postgraduate School, FUT, Minna at my departure from Nigeria with many other colleagues whose names are too numerous to mention are highly appreciated. I am very grateful to Dr. B. O. Aderemi and Dr Mohammed Tijani both of Chemical Engineering Department, and Dr.

Abdul-Raheem Giwa of Department of Textile Science, Ahmadu Bello University (ABU), Zaria, Nigeria,

I also wish to express my profound gratitude to all the members of Parit Buntar Baptist Church. Pastor Rowland Lee and wife, Sister Janet, Bro. Mugan Bunyau and family, Sister Agnes Joseph and husband, Dr. Samuel Padman and wife, Santa, Bro.

Ng Wee, Bro. Ong Tiong Keat and Sister YB Tan Cheng Liang and members of their family. Madam Lim, Sis. Siew Im and others. I am most grateful to you all. God bless you.

I acknowledge the contributions of Elder Sam Victor Olorunsogo and his wife Mummy Rejoice in the Lord for their kindness and financial support when coming to

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Malaysia. May God bless you for your love and kind gesture to me. Also, words will not be enough for me to express my heartfelt gratitude to all members of The Apostolic Church, Minna Area, Nigeria for taking care of my family. My thanks go to my sibling; Mr. and Mrs. Ajibola Olutoye (London, UK), Mr. and Mrs.

Olanrewaju Olutoye (Lagos, Nigeria) Mr. and Mrs. Adaramola Olutoye (Abuja, Nigeria). Others are Pastor and Mrs. Samuel Olutoye, Mr. and Mrs. Oluwasesan Olutoye, Mr. and Mrs. Kehinde Olutoye.

Appreciation goes to the following (without much elaborate encomium, they know their contribution and impact in various capacities). They are: Dr. Uduak George Akpan (Tqvm), Mr. Manase Auta, Dr. Jassim M. Salman, Dr. Victor O. Njoku, Dr.

Solomon O. Bello, Dr. Christopher Akinbile, Saad Nashat, Sunday Adedigba, Abolarinwa A.O.George, Muataz Shakir, Chin Lip Han, Iris Soon Ai Ni and her family (Tqvm for immeasurable assistance), Hadis Amani, Zahra and Fatemeh Gholami (Twins Sister) and other friends in Reaction Engineering and Adsorption (READ) group, for your kindness, help, concern, motivation and moral supports. I appreciate all your efforts, my dear friends. To those who indirectly contributed to this research, your kindness means a lot to me. Thank you very much.

Last but definitely not least, gratitude goes to my father and step mother in Erio- Ekiti, Ekiti State, Nigeria (my origin) for their support, encouragement, understanding, concern and for standing by me during this study. I thank you all for being there always. God will reward you bountifully. Amen!

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DEDICATION

This research is dedicated to God Almighty-The Most High (Jehovah-Elyon-Lord Most High God) for uncountable reasons- Him alone giveth knowledge and wisdom

to whom He pleases.

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vii TABLE OF CONTENTS

Page

ACKNOWLEDGEMENT iii

DEDICATION vi

TABLE OF CONTENTS vii

LIST OF TABLES xiii

LIST OF FIGURES xvi

APPENDICES LIST OF PLATES

xxii xxiii

LIST OF SYMBOLS xxiv

LIST OF ABBREVIATIONS xxv

ABSTRAK xxvii

ABSTRACT xxix

CHAPTER 1 INTRODUCTION

1.0 Global demand for alternative energy source 1

1.1 Transesterification process 4

1.1.1 Homogeneous transesterification process 6

1.1.2 Heterogeneous transesterification process 8

1.2 General uses and properties of biodiesel 10

1.3 Problem Statement 12

1.4 Research Objectives 16

1.5 Scope of study 17

1.6 Organization of the Thesis 19

Chapter 1 (Introduction) 19

Chapter 2 (Literature review) 19

Chapter 3 (Materials and methods) 19

Chapter 4 (Results and Discussions) 20

Chapter 5 (Thermodynamics and kinetics of the process) 20

Chapter 6 (Conclusions and recommendations) 21

CHAPTER TWO LITERATURE REVIEW

2.0 Introduction 22

2.1 The origin and application of vegetable oil as diesel fuel 22 2.2 Fatty acid methyl ester (FAME) and transesterification 27

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2.3 Solid Catalysis in Biodiesel Production 30

2.4 Fatty acids compositions of some edible and non-edible oils 51 2.5 Structure formula for fatty acids and biodiesel 52 2.6 Parameters involve in the transesterification of oil 54 2.6.1 Effect of free fatty acids in oil during transesterification 54

2.6.2 Effect of water content in feedstock 56

2.6.3 Effect of catalyst loading on the production of FAME 57 2.6.4 Effect of temperature on transesterification of oil 58

2.6.5 Alcohol and molar ratio employed 59

2.7 Catalyst reusability and regeneration 60

2.8 Kinetic studies 61

2.8.1 Kinetic of transesterification reaction of triglycerides 62

2.8.2 Kinetic modeling 63

2.8.3 Rate constant and activation energy 67

2.8.4 Deactivation kinetics and intra-particle diffusion effects 68

2.8.5 Summary 68

CHAPTER THREE MATERIALS AND METHODS

3.1 Introduction 70

3.2 Materials and methods 70

3.3 Equipment 73

3.3.1 Equipment for FAME synthesis 73

3.3.2 Catalyst characterization 74

3.3.2 (a) Nitrogen physisorption isotherms 76

3.3.2 (b) X-ray diffraction 76

3.3.2 (c) Scanning electron microscopy 77

3.3.2 (d) Fourier transformed infrared spectroscopy 77 3.3.2 (e) Transmission electron microscopy (TEM) 78

3.3.3 Purification and analysis of product 78

3.3.3 (a) Gas chromatography (GC) 78

3.3.3 (b) Ultra-Fast Liquid Chromatography (UFLC) analyzer 80

3.3.3 (c) Flash point tester 81

3.3.3 (d) Moisture content determination and refractive

index 82

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3.3.3 (e) Viscosity measurement 83

3.4 Synthesis of mixed oxides catalysts 84

3.4.1 Experiment to establish a basis for catalyst

preparation/treatment procedure 85

3.4.2 Preparation KMgZnO 86

3.4.3 Synthesis of MgO alone with KOH 87

3.4.4 Synthesis of ZnO alone with KOH 88

3.4.5 Preparation of KMgZnO with reverse composition 88 3.4.6 Synthesis of MgZnO catalyst precipitated separately with

KOH and NH4OH 89

3.4.7 Preparation of MgZnAlO catalyst 90

3.5 Transesterification of vegetable oils with methanol 91 3.5.1 Process optimization and response surface methodology 93 3.5.2 Central Composite Rotatable Design (CCRD) 94 3.5.3 Model Fitting and Statistical Analysis 96

3.5.4 Desirability Approach 98

3.5.5 Experimental Data Repeatability 99

3.6 3.6 Transesterification of vegetable oil with methanol for kinetic

analysis 99

3.6.1 Determination of the surface acidity and basicity of

synthesized catalyst 101

3.6.2 Separation and analysis of fatty acid, FAME, MG, DG and

TG in oil sample 102

3.7 Thermodynamics of the reversible transesterification reaction 103 CHAPTER FOUR RESULTS AND DISCUSSION

4.0 Introduction 105

4.1 Synthesis of the mixed metal oxides catalyst 106

4.1.1 The basis for the catalyst screening 106

4.1.2 Investigation into the effects of catalyst

preparation/treatment conditions 107

4.1.3 Characterization of the synthesized catalyst 1 111 4.1.4 Textural properties of variously developed catalyst 1 112

4.1.5 Surface morphology 115

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4.1.6 Elemental composition of the synthesized catalyst and XRD

measurement 117

4.1.7 Fourier transforms infrared (FTIR) analysis 122 4.1.8 Catalyst optimization and Design of experiment for

KyMg1-xZn1+xO3 125

4.1.9 Design of experiments 125

4.1.10 Model analysis for the catalyst activity response 127 4.1.11 Interaction beteween factors during activity tests for

KyMg1-xZn1+xO3 130

4.1.12 Optimization and model validation of

KyMg1-xZn1+xO3 catalyst by response surface methodology 133 4.1.13 The study of optimized catalyst activity in the

transesterification of palm oil with different operating

parameters using DOE 133

4.1.14 Model analysis and process optimization of the parameters

influencing transesterification reaction 141 4.1.15 Activity test and characterization of catalyst 1 for stability

and reusability 144

4.1.16 Short coming of catalyst 1 and justication for the the

development of catalyst 2 152

4.2 Development and synthesis of catalyst 2 152

4.2.1 Characterization of the synthesized catalyst 2 154

4.2.2 Textural properties of catalyst 2 155

4.2.3 Surface morphology of catalyst 2 158

4.2.4 Elemental composition (microstructure) of the

Mg0.34Zn1.66O2 synthesize catalyst and XRD measurements 159 4.2.5 Identification of the surface functional group for the

synthesized catalyst 2 163

4.2.6 Catalytic activity of magnesium-zinc mixed oxides

(Mg1-xZn1+xO2) catalyst in the production of FAME 164 4.2.7 Correlation of models for RPO and WCPO in terms of the

various parameters 175

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4.2.8 Effect of water and free fatty acid in the oil 177 4.2.9 Model analysis and optimization of WCPO

transesterification with methanol 179

4.2.10 Catalytic activity tests for reusability, stability and

characterization of catalyst 2 181

4.2.11 Catalyst development challenges and comparative

advantage of catalyst 2 196

4.3 The development and synthesis of catalyst 3 198 4.3.1 Characterization of the as-synthesized catalyst 3 202 4.3.2 Textural properties of the synthesized catalyst 3 203 4.3.3 Surface morphology by TEM and SEM analysis 206 4.3.4 Elemental composition and microstructure of the

synthesized catalyst 3, X-ray diffraction (XRD) analysis,

FTIR and TG-DTA measurements 209

4.3.5 (a) Effect of oil properties and characterization on

the transesterification reaction 216

4.3.5 (b) Catalytic activity of Al2O3 modified mixed oxides

catalyst (catalyst 3) in the production of FAME 218 4.3.5 (c) Effect of catalyst loading, properties and reaction

temperature on the trans-esterification reaction 218 4.3.5 (d) Effect of reaction temperature and methanol/oil

ratio on the transesterification reaction 224 4.3.5 (e) Effect of reaction time on FAME yield 225 4.3.6 General model for the different vegetable oils from the

design of experiments using catalyst 3 and the evaluation of

process optimum conditions 227

4.3.7 Yield of CJO and fatty acid profile 236 4.3.8 Characterization and properties of FAME obtained from

CJO, refined PO and WCPO 238

4.3.9 Catalyst stability, reusability tests and characterization of

catalyst 3 243

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xii CHAPTER FIVE

THERMODYNAMICS AND KINETICS OF THE PROCESS:

KINETIC STUDY AND DETERMINATION OF KINETIC REACTION PARAMETERS FOR TRANSESTERIFICATION

5.0 Introduction 248

5.1 Reaction kinetic model and analysis of kinetic data 248 5.1.1 Transesterification reaction of crude jatropha oil with and

without catalyst 254

5.2 The thermodynamics of process 262

5.3 Effect of temperature 264

5.4 Catalyst deactivation model and mechanism 270

5.5 The mechanism for the basic site catalytic reaction 274

CHAPTER SIX

CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions 278

6.2 Recommendations 282

REFERENCES 283

APPENDICES 301

LIST OF PUBLICATIONS 317

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LIST OF TABLES

Page Table 2.1 Compilation of homogeneous and heterogeneous catalysts

used in transesterification at low and extremely high

conditions 34-49

Table 3.1 Sources and suppliers of feedstock and chemicals used for

the study 72-73

Table 3.2

Factors and corresponding levels of experimental design

used for the catalyst preparation. 86

Table 3.3 Factors and corresponding levels for the response

surface design of independent variables used in

transesterification 93

Table 4.1 Various levels of chemical combinations of metals

employed in for the synthesis of catalyst 1 108 Table 4.2 Catalyst formulation and the treatment methods employed

during synthesis 108

Table 4.3 Preliminary activity test of selected catalyst 1 subjected to

dual treatment at different calcination temperature 109 Table 4.4 BET surface area, total pore volume and average pore

diameter of the synthesized catalyst 113

Table 4.5 Elemental composition of the synthesized catalyst 120 Table 4.6 Experimental design matrix and catalyst activity response 127 Table 4.7 Analysis of variance of the response surface model 128 Table 4.8 Optimized conditions for KyMg1-xZn1+xO3 catalyst 134 Table 4.9 Experimental design matrix and response for catalyst

activity test 135

Table 4.10 Analysis of variance of the response surface 142 Table 4.11 The preset goal with constraints for all parameters and

response for optimized conditions 144

Table 4.12 Results of reusability and leaching tests 145 Table 4.13 Development and empirical formulation of catalyst 2 154 Table 4.14 BET surface area, total pore volume and average pore

diameter of the synthesized Mg0.34Zn1.66O2 catalyst 155

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Table 4.15 EDX of Mg0.34Zn1.66O2 catalyst prepared by dual

precipitating media 159

Table 4.16 FTIR spectra analysis and peak assignment for catalyst 2 164 Table 4.17 Levels of the transesterification condition variables for

WCPO 166

Table 4.18a Comparative results of the activity of as synthesized

K2Mg0.3Zn1.7O3 and Mg0.34Zn1.66O2 catalysts on WCPO 167

Table 4.18b FAME yield of catalyst 2 on RPO 168

Table 4.19 Value of coefficient defined in general model equation for

each catalyst 170

Table 4.20 Effect of stirring with and without catalyst at room and

elevated temperature during transesterification 171 Table 4.21 Results of model correlation for both RPO and WCPO 176 Table 4.22 Analysis of variance for the response surface model of

WCPO 180

Table 4.23 Activity of Apptd and Kpptd catalysts in reusability and

regeneration tests 184

Table 4.24 Elemental analysis for as synthesized Apptd and Kpptd

catalysts 186

Table 4.25 Various levels of chemical combination of the metals

employed in catalyst synthesis for catalyst 3 199 Table 4.26 FAME yield (%) obtained during preliminary test run for

activity of catalyst 3 with WCPO as feedstock 201 Table 4.27 BET surface area, total pore volume and average pore

diameter of selected catalyst 3 with KyMg1-xZn1+x Al(2-y)/3O3

203

Table 4.28 Elemental composition of catalyst 3 210

Table 4.29 FTIR spectra analysis and peak assignment for catalyst 3

with and without Al inclusion 214

Table 4.30 Some properties of five types of oil before trans-

esterification with methanol 216

Table 4.31 Design of experiment and responses for five types of oil

using catalyst 3 219

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Table 4.32 Values of the determined coefficients in the five-type oil general model

229

Table 4.33 Process optimum conditions for five-type vegetable oil 230 Table 4.34 Comparison of results obtained with synthesized catalyst 3 231-

234 Table 4.35 FAME properties of some samples of oil after

transesterification with methanol 239

Table 5.1 Values of experimental and kinetic model parameters 253 Table 5.2 Kinetic model parameters for the zero and apparent first

order reaction for the transesterification of crude jatropha oil 267 Table 5.3 Reaction kinetics of transesterification between palm oil and

methanol under subcritical conditions 269

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LIST OF FIGURES

Page Figure 2.1 Typical process flow diagram for biodiesel production 31 Figure 3.1 Schematic flow chart of experimental work 71 Figure 3.2 Schematic diagram of PARR 4842 reactor 75 Figure 3.3 Schematic diagram of CCRD as a function of three

variables, X1, X2 and X3 according to 23 factorial design. 96 Figure 4.1 FAME yield (%) versus transesterification time (min) during

test of activity with as synthesized catalyst K2Mg0.3Zn1.7O3 at different treatment methods: Hot and cold treatment with methanol/oil ratio 6:1, catalyst loading 1.404 wt %, reaction

time 12 h and temperature 150 oC. 110

Figure 4.2 Initial test for the effect of reaction period on the yield of FAME at methanol/oil ratio 6:1, catalyst loading 1.404 wt

%, reaction time 6 h and temperature 150 oC. 112 Figure 4.3 Adsorption-desorption isotherms for catalyst 1; (a)

K2Mg0.3Zn1.7O3 (b) K2Mg1.7Zn0.3O3 calcined at temperature

460 ± 1 oC and time 4.5 h 114

Figure 4.4 Figure 4.4. SEM image of synthesized catalyst samples calcined at 4.5 h: (a) K2Mg0.3Zn1.7O3, 600 oC, (b)

K2Mg0.3Zn1.7O3, 460 ± 1 oC, (c) K2Mg0.7Zn1.3O3, 600 oC, (d) K2Mg0.7Zn1.3O3, 460 ± 1 oC, (e) ZnO at 460 ± 1 oC for 4.5 h (f) MgO, 460 ± 1 oC, (g) K2Mg1.7Zn0.3O3 (swapped Mg/Zn metal), 460 ± 1 oC.

116 Figure 4.5 Energy dispersive X-ray (EDX) spectra of the synthesized

catalysts:(a)K2Mg0.3Zn1.7O3; (b) K2Mg1.7Zn0.3O3; (c) MgO

and (d) ZnO all calcined at 460 ± 1 oC for 4.5 h 119 Figure 4.6 XRD pattern for the synthesized catalyst; (a) K2Mg0.3Zn1.7O3;

(b) K2Mg1.7Zn0.3O3 both calcined at 460 ± 1 oC for 4.5 h. 121 Figure 4.7 FTIR spectra for 4 samples: (a) K2Mg0.3Zn1.7O3 (b)

K2Mg1.7Zn0.3O3 (c) MgO and (d) ZnO calcined at 460 ± 1 oC

for 4.5 h 123

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Figure 4.8 3-D surface response plot for the interactive effect of Mg/Zn ratio and time on FAME content (at calcination temperature

= 460 ± 1 oC) 130

Figure 4.9 3-D surface response plot for the interactive effect of calcinations temperature and calcination time (at Mg/Zn

ratio = 4.81). 131

Figure 4.10 3-D surface response plot for the interactive effect of Mg/Zn ratio and calcination temperature on FAME content (at

calcination time = 4.5 h). 132

Figure 4.11 3-D response surface plot of FAME content showing effect of catalyst loading and time (with two of the parameters fixed; methanol to oil molar ratio = 12, and temperature =

175 o C). 136

Figure 4.12 3-D response surface plot of FAME content showing effect of catalyst loading and temperature (with two of the parameters fixed; methanol to oil molar ratio = 12, and time

= 3 h). 137

Figure 4.13 3-D response surface plot of FAME content showing effect of methanol to oil molar and time (temperature = 175 °C,

catalyst loading = 2.5wt %). 138

Figure 4.14 3-D response surface plot of FAME content showing effect of catalyst loading and methanol to oil molar (temperature

=175 °C, time = 3 h). 139

Figure 4.15 SEM images of K2Mg0.34Zn1.66O3: (a) image before and (b) image after used for one cycle in transesterification at methanol/oil ratio 6:1, catalyst loading 1.404 wt %,

temperature 150 oC and reaction time 6 h. 147 Figure 4.16 EDX spectra for K2Mg0.34Zn1.66O3: (a) spectrum before and

(b) spectrum after used for one cycle in transesterification at methanol/oil ratio 6:1, catalyst loading 1.404 wt %,

temperature 150 oC and reaction time 6 h. 148 Figure 4.17 XRD spectra for K2Mg0.34Zn1.66O3 (a) spectrum before and

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(b) spectrum after used for one cycle in transesterification at methanol/oil ratio 6:1, catalyst loading 1.404 wt %,

temperature 150 oC and reaction time 6 h. 149 Figure 4.18 FTIR spectra for K2Mg0.34Zn1.66O3 (a) spectrum before (b)

spectrum after used for one cycle in transesterification at methanol/oil ratio 6:1, catalyst loading 1.404 wt %,

temperature 150 oC and reaction time 6 h. 151 Figure 4.19 Adsorption-desorption isotherms for catalyst 2 samples

calcined at temperature 460 ± 1 oC and time 4.5 h; (a)

NH4OH precipitated and (b) KOH precipitated 157 Figure 4.20 SEM image of synthesized catalyst samples:(a) SEM image

of NH4OH precipitated catalyst sample and (b) SEM image of KOH precipitated catalyst sample both calcined at 460 ±

1 oC at 4.5 h. 159

Figure 4.21 EDX spectra of synthesized catalyst samples of catalyst 2:

(a) EDX image of NH4OH precipitated catalyst sample and (b) EDX image of KOH precipitated catalyst sample both

calcined at 460 oC for 4.5 h 160

Figure 4.22 XRD patterns of the as-synthesized catalyst: (a) NH4OH precipitated sample and (b) KOH precipitated sample both

calcined at 460 ± 1 oC for 4.5 h. 161

Figure 4.23 FTIR spectra analysis for the as-synthesized catalyst for A12

and K12 showing the identification of specific band widths:

A12 (NH4OH precipitated) and K12 (KOH precipitated). 163 Figure 4.24 3-D response surface plot of FAME content showing effect

of methanol to oil molar ratio and catalyst loading(with two of the parameters fixed; temperature = 188 oC, and time =

4.25 h). 171

Figure 4.25 3-D response surface plot of FAME content showing effect of catalyst loading and temperature (methanol to oil molar

ratio = 9, time = 4.25 h). 172

Figure 4.26 3-D response surface plot of FAME content showing effect of methanol to oil molar ratio and temperature (time = 4.25

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h, catalyst loading = 3 wt %). 174

Figure 4.27 3-D response surface plot of FAME content showing effect of methanol to oil molar ratio and time (with two of the parameters fixed; catalyst loading = 3wt %, and temperature

= 188 oC). 174

Figure 4.28 Dependency of FAME yields on various parameters. (a) Methanol/oil ratio at catalyst loading of 4.19 wt %, temperature 186 oC, and reaction time 4 h; (b) Catalyst loading at methanol/oil ratio 10:1, temperature 186 oC, and reaction time 4 h; (c) Temperature at methanol/oil ratio 10:1, catalyst loading of 4.19 wt %, and reaction time 4 h; and (d) Reaction time at methanol/oil ratio 10:1, catalyst loading of 4.19 wt %, and temperature 186 oC.

182- 183 Figure 4.29 SEM images of Mg0.34Zn1.66O2 for Ammonium precipitated

catalyst (a) before used, (b) After 4th regeneration and (c) After 4th reuse a subjected to similar initial heat treatment at

temperature 460 ± 1 oC, 4.41 h. 185

Figure 4.30 SEM images of Mg0.34Zn1.66O2 for potassium hydroxide precipitated catalyst:(a) before use, (b) after 4th regeneration, and (c) after 4th reuse all subjected to similar initial heat

treatment at temperature 460 ± 1 oC, 4.41 h. 187 Figure 4.31 EDX spectra for Mg0.34Zn1.66O2for Ammonium precipitated

catalyst (a) Before used, (b) After 4th regeneration and (c) After 4th reuse all subjected to similar initial heat treatment at

temperature 460 ± 1 oC, 4.41 h. 189

Figure 4.32 EDX spectra for Mg0.34Zn1.66O2 for potassium hydroxide precipitate catalyst: (a) before use, (b) after 4th regeneration, and (c) after 4th reuse all subjected to similar initial heat

treatment at temperature 460 ± 1 oC, 4.41 h. 190 Figure 4.33 XRD patterns of representative catalyst precipitated with

ammonium (Apptd) and potassium (Kpptd) hydroxides after 4

cycles. 191

Figure 4.34 FTIR spectra for Mg0.34Zn1.66O2 Apptd catalyst,(a) Before use,

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(b) After 4th regeneration and (c) After 4th reuse. 193 Figure 4.35 FTIR spectra for Mg0.34Zn1.66O2 Kpptd catalyst, (a) Before

use, (b) After 4th regeneration and (c) After 4th reuse. 194 Figure 4.36 Nitrogen adsorption/desorption isotherms of catalyst 3: (a)

Mg0.7Zn1.3Al0.67O3 calcined at temperature 460±1 oC and time 4.41 h, (b) Typical representative catalyst 3 calcined at

temperature 460 ± 1 oC and time 4.41 h. 205 Figure 4.37 TEM images for KyMg1-xZn1+x Al(2-y)/3O3catalyst where (a) x

= 0.1, (b) x = 0.3, (c) x = 0.5 and (d) x = 0.7 with

magnification at 35 KX. 207

Figure 4.38 SEM images for KyMg1-xZn1+x Al(2-y)/3O3 where (a) x = 0.1,

and (b) x = 0.3, calcined at temperature 460 ± 1 oC, 4.41 h. 209 Figure 4.39 XRD spectra for the synthesized catalyst 3: (a) Ammonia

precipitated Al modified catalyst showing ZnO hexagonal structure, Al2O3 orthorhombic structure, and ZnAl oxide (Zn3Al94O144/94Al2O3.6ZnO)-monoclinic structure. (b) Ammonia precipitated unmodified catalyst (without Al) showing both hexagonal ZnO and MgO with Cubic MgZn

(Mg2Zn11). 211

Figure 4.40 TGA and DTA curves for the synthesized catalyst 3,

Mg1-xZn1+xAl (2-y)/3O3 (a) when x = 0.3 and (b) x = 0.5; y = 0 212 Figure 4.41 FTIR spectra for the synthesized catalyst 3 (a) With Al and

(b)Without Al. 214

Figure 4.42 3-D response for methanol/oil ratio and catalyst loading, wt

% for (a) refined PO, (b) WCPO, (c) PKO, (d) CCO, and (e)

CJO at temperature = 170oC. 220

Figure 4.43 3-D response for temperature (oC) and catalyst loading (wt

%) for (a) RPO, (b) WCPO, (c) PKO, (d) CCO, and (e) CJO

at methanol/oil ratio = 14. 222

Figure 4.44 3-D surface response plot for temperature (oC) and methanol/oil ratio for (a) RPO, (b) WCPO, (c) PKO, (d)

CCO, and (e) CJO at catalyst loading = 6 wt %. 226

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Figure 4.45 Comparison between the regeneration and reusability tests

for catalyst 3. 245

Figure 4.46 TEM images of Mg0.7Zn1.3Al2/3O3:(a) Before use, (b) After 5th regeneration cycle and (C) After 5th reuse cycle all

calcined at 460 ± 1 oC for 4.41 h 246

Figure 5.1 (a-d)

Plot of triglyceride concentration against reaction time with

catalyst 3: (a) At 150 oC and (b) At 160 oC. 251 Figure 5.2

(a-d)

Plot of ln CA/CAo against reaction time with catalyst 3 at: (a)

150 oC, (b) 160 oC, (c) 170 oC and (d) 182 oC 252 Figure 5.3 Plot of triglyceride concentration against reaction time at

temperature, T = 182 oC: (a) With catalyst and (b) Without

catalyst. 255

Figure 5.4 Plot of triglyceride concentration against reaction time at temperature, T = 150 oC: (a) With catalyst and (b) Without

catalyst. 255

Figure 5.5 Plot of triglyceride concentration against reaction time at temperature, T = 160 oC: (a) With catalyst and (b) Without

catalyst. 256

Figure 5.6 Plot of triglyceride concentration against reaction time at temperature, T = 170 oC: (a) With catalyst and (b) Without

catalyst. 256

Figure 5.7 Representative profile of % FAME, DG, MG, and TG against reaction time at temperature of T = 150 oC without

catalyst: (a) With catalyst and (b) without catalyst. 258 Figure 5.8

(a-d)

Representative plots of TG conversion to FAME, DG, MG, and residual unconverted TG with reaction time at T = 150

oC with catalyst 3: (a) FAME content with catalyst, (b) FAME content without catalyst, (c) MG content with

catalyst, and (d) MG content without catalyst. 260 Figure 5.8

(e-h)

Representative plots of TG conversion to FAME, DG, MG, and residual unconverted TG with reaction time at T = 150

oC with catalyst 3: (e) DG content with catalyst, (f) DG

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content without catalyst, (g) Residual TG content with

catalyst, and (h) Residual TG content without catalyst 261 Figure 5.9 Representative FAME yield plot and residual FFA in

product at temperature T = 150 oC: (a) With application of

catalyst 3 and (b) Without catalyst 262

Figure 5.10 Effect of temperature on the initial concentration of triglyceride at 1 h reaction time

265

Figure 5.11 Arrhenius plot of rate constant versus temperature for the transesterification of crude jatropha oil with methanol at

constant catalyst loading of 3.32 wt % 266

Figure 5.12 Plot of FAME yield (%) versus reaction time (min) at

different temperatures at reaction time of 6 h 276

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xxiii APPENDICES

Page APPENDIX A

Table A-1 Fatty acid composition of some common edible fats and

oils, % by weight of total fatty acids 301

Table A-2 Selected properties of some common fatty acids and esters 303

APPENDIX B

Figure B-1 Calibration curve for triglyceride (crude jatropha oil) 305

APPENDIX C

Figure C-1 Representative profile of % FAME, DG, MG, and TG against reaction time at temperature of T = 160 oC: (a) With catalyst 3 and (b) without catalyst

311

Figure C-2 (a-d)

Plots of TG conversion to FAME, DG, MG, and residual unconverted TG with reaction time at T = 160 oC with catalyst 3: (a) FAME content with catalyst, (b) FAME content without catalyst, (c) MG content with catalyst, and (d) MG content without catalyst

312

Figure C-2 (e-h)

Representative plots of TG conversion to FAME, DG, MG, and residual unconverted TG with reaction time at T

= 160 oC with catalyst 3: (e) DG content with catalyst, (f) DG content without catalyst, (g) Residual TG content with catalyst, and (h) Residual TG content without catalyst

313

Figure C-3 Representative profile of % FAME, DG, MG, and TG against reaction time at temperature of T = 170 oC: (a) With catalyst 3 and (b) without catalyst

314

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xxiv Figure C-4

(a-d)

Representative plots of TG conversion to FAME, DG, MG, and residual unconverted TG with reaction time at T = 170 oC with catalyst 3: (a) FAME content with catalyst, (b) FAME content without catalyst, (c) MG content with catalyst, and (d) MG content without

catalyst. 315

Figure C-4 (e-h)

Representative plots of TG conversion to FAME, DG, MG, and residual unconverted TG with reaction time at T = 170 oC with catalyst 3: (e) DG content with catalyst, (f) DG content without catalyst, (g) Residual TG content with catalyst, and (h) Residual TG content without

catalyst. 316

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xxv

LIST OF PLATES

Page

Plate 3.1 The PARR 4842 reactor 75

Plate 3.2 Gas chromatography 80

Plate 3.3 Ultrafast Liquid Chromatography 81 Plate 3.4 Flash point tester equipment 82 Plate 3.5 Coulometric Karl Fischer Titration Analyzer 83

Plate 3.6 Viscosity measurement set-up 85

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xxvi

LIST OF SYMBOLS

Symbol Description Unit

A Pre-exponential factor L mol-1 min-1

C, Ct Concentration at any time, t mg/L

C0, CA0 Initial concentration mg/L

Ea Activation energy J/mol

H Hysteresis type

k Rate constant (1/min)

kr True rate constant mg/(L.min)

K Dimensionless constant

KA Adsorption equilibrium constant L/mg

OH Hydroxyl radical

OH Hydroxyl ion

P Pressure bar

P0 Initial pressure bar

rA0 Initial rate of reaction mg/(L.min)

R2 Correlation coefficient

θAds Surface coverage of adsorbed

species

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xxvii

LIST OF ABBREVIATIONS

AKpptd Ammonium hydroxide precipitated

ASTM American Standards of Testing and Measurements

AGO Automotive gas oil

Al Aluminium

AC Activated carbon

BET Brunauer–Emmet–Teller

BJH Barret–Joyner–Halenda

CCO Coconut oil

CJO Crude jatropha oil

CO2 Carbon dioxide

DG Diglyceride

DOE Design of experiments

EDX energy dispersive X-ray

EN European Standard

FAME Fatty acid methyl ester

FTIR Fourier transform infrared

HCl Hydrochloric acid

H2O Water

K Potassium

Kpptd Potasium hydroxide precipitated

KNO3/Al2O3 Potasium nitrate on alumina support

KOH Potasium hydroxide

L-H Langmuir-Hinshelwood

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Mg Magnesium

MG Monoglyceride

PKO Palm kernel oil

RSM Response surface methodology

RPO Refined pal oil

SEM Scanning electron microscopy

TEM Transmission electron microscopy

TG Triglyceride

WCPO Waste cooking palm oil

wt % Weight percent

XRD X-ray diffraction

Zn Zinc

ZnO Zinc oxide

ZnCl2 Zinc chloride

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xxix

SINTESIS, PENCIRIAN DAN AKTIVITI MANGKIN CAMPURAN OKSIDA LOGAM (Mg, Zn, Al) BAGI TRANSESTERIFIKASI SISA MINYAK MASAK KELAPA SAWIT, MINYAK BOLEH DIMAKAN DAN TIDAK BOLEH DIMAKAN

ABSTRAK

Biodiesel, yang juga dikenali sebagai “fatty acid methyl esters” (FAME), merupakan alternatif bahan api yang boleh dihasilkan melalui proses pemangkinan homogen atau heterogen. Biodiesel adalah bahan api yang boleh diperbaharui dan pembakarannya yang mesra alam jika dibandingkan dengan fosil (petroleum mentah). Kajian ini memberi tumpuan kepada pembangunan dan sintesis mangkin pepejal melalui gabungan beberapa logam untuk menghasilkan mangkin komposit dengan formula Mg1-xZn1+xAl(2-y)/3O3 (at y = 0 dan 0.1≤ x ≤0.9) sesuai untuk menghasilkan FAME daripada pelbagai sumber minyak sayuran yang boleh dimakan dan tidak boleh dimakan (minyak kelapa sawit ditapis (RPO), sisa minyak masak sawit (WCPO), minyak kelapa (CCO), minyak isirung sawit (PKO) dan minyak jatropha (CJO)) terutamanya daripada minyak kelapa sawit kerana Malaysia adalah salah satu pengeluar terbesar di dunia dan ia boleh didapati dalam kuantiti komersil.

Mangkin yang disintesis dengan aktiviti yang dipertingkatkan dalam transesterifikasi telah dibangunkan dan disediakan melalui kaedah pemendakan bersama campuran hidroksida logam-logam daripada sebatian nitrat masing-masing yang diperolehi dalam tiga peringkat mangkin 1 (KyMg1-xZn1+xO3), mangkin 2 (Mg1-xZn1+xO2) dan mangkin 3 (Mg1-xZn1+xAl(2-y)/3O3). Mangkin-mangkin tersebut tertakluk kepada suhu 460 ± 1 oC untuk 4.41 h. Prestasi mangkin diperolehi daripada pencirian sifat-sifat tekstur,“surface scanning electron microscopy”(SEM) untuk morfologi mikrostruktur dan permukaan dan “X-ray diffraction”(XRD) dan “Fourier Transformed Infra Red”

(FTIR) untuk menganalisis struktur dan kumpulan berangkap masing-masing. Hasil

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analisis menunjukkan bahawa mangkin yang disediakan terbukti berkesan dalam transesterifikasi dengan 87% FAME telah dihasilkan bagi mangkin 1 menggunakan RPO, 87% dan 83% bagi mangkin 2 menggunakan WCPO dan RPO masing-masing.

Walaubagaimanapun, nilai larut lesap yang tinggi bagi mangkin 1 iaitu 13%, hasil yang rendah dan luas permukaan yang rendah iaitu 9.67 m2/g bagi mangkin 2 menyebabkan pengubahsuaian selanjutnya diperlukan. Mangkin 3 menunjukkan prestasi yang lebih baik apabila aluminium, dimasukkan dengan meningkatkan luas permukaan, larut lesap kurang dalam bentuk ion dalam lingkungan 1-2% dan 94%

FAME dihasilkan untuk minyak tidak boleh makan, asid lemak dan kandungan kelembapan minyak mentah jatropha melalui cara sintesis satu kelompok. Sifat amfoterik mangkin 3 dengan kehadiran aluminium dalam komposit ini bertanggungjawab meningkatkan prestasi dan ia boleh diguna sebanyak lima kitaran.

Pelbagai parameter antaranya nisbah metanol kepada molar minyak (9-18), jumlah mangkin (1.5-10.5 wt %), suhu (150-190 oC) dan masa tindakbalas (6 h) telah dikaji.

Parameter-parameter ini telah dioptimumkan dengan penggunaan perisian reka eksperimen, bagi memperoleh keadaan optimum iaitu (88% FAME; nisbah metanol kepada minyak, 11:1; jumlah mangkin, 3.32 wt % pada suhu 182 oC) untuk mangkin 3 menggunakan minyak jatropha, tekanan autogenous dalam linkungan 12-22 bar dan suhu didapati menjadi salah satu parameter yang ketara. Analisis produk menunjukkan persamaan dengan piawaian American Standards for Testing and Measurements (ASTM) dan European Union Standards (EN) bagi biodiesel. Kajian kinetik juga dikaji untuk minyak jetropha pada keadaan optimum dan tindakbalas dijelaskan dengan kadar tertib pertama. Di samping itu, nilai-nilai tenaga bebas Gibb (ΔG, J/mol), tenaga pengaktifan (Ea, kJ/mol) dan pra-eksponen faktor A, L/mol/min) adalah -1285.6, 161.4 and 1.0 x 10-4, masing-masing.

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xxxi

SYNTHESIS, CHARACTERIZATION AND ACTIVITY OF MIXED METAL OXIDE (Mg, Zn, Al) CATALYSTS FOR TRANSESTERIFICATION OF WASTE COOKING PALM OIL, EDIBLE AND NON-EDIBLE OILS

ABSTRACT

Biodiesel, also known as fatty acid methyl esters (FAME), is an alternative fuel that could be obtained by homogeneous or heterogeneous catalytic processes. It is renewable and its combustion is environment friendly compared to fossil (crude petroleum). This research focused on the development and synthesis of solid catalyst from combination of some metals to produce composite catalyst with KyMg1-

xZn1+xAl(2-y)/3O3 (at y = 0 and 0.1≤ x ≤0.9) suitable to produce FAME from different vegetable oils-edible and non-edible sources (refined palm oil (RPO), waste cooking palm oil (WCPO), coconut oil (CCO), palm kernel oil (PKO) and crude jatropha oil (CJO)) most specifically from palm oil since Malaysia is one of the world’s largest producer and it’s available in commercial quantity. The synthesized catalyst with an enhanced activity in transesterification was developed and prepared by co- precipitation of the mixed metal hydroxides from their nitrates compounds achieved in three stages named as catalyst 1 (KyMg1-xZn1+xO3), catalyst 2 (Mg1-xZn1+xO2) and catalyst 3 (Mg1-xZn1+xAl(2-y)/3O3). All the catalysts were subjected to heat treatment at 460 ± 1 oC for 4.41 h. Insights to the catalyst performance was obtained from characterization for its textural properties, surface scanning electron microscopy (SEM) for microstructure and surface morphology and, X-ray diffraction (XRD) and Fourier Transformed Infra Red (FTIR) for structural and functional groups analysis, respectively. The analysis revealed that the developed catalysts proved to be effective in transesterification with FAME yields of 87 % for catalyst 1 using RPO, 87 % and 83 % for catalyst 2 using WCPO and RPO, respectively. However, high value of leaching for catalyst 1(13 %), low yield and low surface area (9.67 m2/g) for

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catalyst 2 make further modification imperative. Catalyst 3 performed better when Al was incorporated with improved surface area, tolerable leaching of 1-2 % and FAME yield of 94 % for non-edible, high fatty acid and moisture content CJO in one-batch synthesis. The amphoteric nature of catalyst 3 with inclusion of Al in the composite is responsible for its high performance and it is reusable over five cycles. Various parameters such as methanol to oil molar ratio (9-18), catalyst loading (1.5-10.5 wt.

%), temperature (150-190 oC) and reaction time (6 h) were investigated. These parameters were optimized with the used of design of experiment software, to obtain optimum conditions (88 % FAME; methanol to oil ratio, 11:1; catalyst loading, 3.32 wt. % at temperature 182 oC) for catalyst 3 using CJO, autogenous pressure range of 12-22 bar and temperature was found to be one of the most significant parameters.

Analysis of the product showed agreement with American Standards for Testing and Measurements (ASTM) and European Union Standards (EN) for biodiesel. Kinetic study was investigated using CJO at the optimum conditions and the reaction was described by first order rate. In addition, values of Gibb’s free energy (∆G, J/mole), activation energy (Ea, kJ/mole) and pre-exponential factor (A, L/mol/min) are - 1285.6, 161.4 and 1.0 x 10-4, respectively.

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1

CHAPTER 1 INTRODUCTION

1.0 Global demand for alternative energy source

Recent research showed that there is increased global awareness in the utilization of alternative (renewable) sources of energy (Adelman and Watkins, 2008). The reason for this has been the increase in the cost of energy produced from fossil fuels coupled with the fact that it is a finite resource; it grossly affects the environment (Phan and Phan, 2008). There is the need to evolve new measures, in terms of appropriate technology and resources, to promote a shift from fossil fuels.

Due to astronomical growth in world population and rapid industrialization which are direct consequence of increased technological breakthrough in almost all spheres of life, it is believed that the global energy demand will definitely increase. Thus, the search for the renewable resources such as solar, wind, water, biomass and other clean energy sources will surge in demand and eventually account for the vast majority of overall energy usage in the near future.

The increasing decline in crude oil reserves has made alternative energy sources inevitable and of great importance. This is in the light of increasing campaign for cleaner burning fuels in order to safeguard the environment and protect man from inhalation of toxic substances. The exhaust from petroleum diesel is known to be carcinogenic in nature, since they contain polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons (PAHs and NPAHs), carbon monoxide, sulphates, and particulate matter (Canakci and Gerpen, 1999).

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2

A renewable resource is a natural resource that can be replaced or replenished by natural processes at a higher or equal rate to its rate of consumption. The renewable resources are part of the natural environment and constitute what is known as the eco-system. The world-wide energy demand is quite huge and more than 80%

of this energy is currently supplied by fossil fuels, coal, oil or gas (Chapman, 1974;

Cleveland et al., 2000; Farrell and Brandt, 2006). Fossil fuels are non-renewable finite resource. The shrinking supply of this resource globally will not make it possible for continued dependence on it for a longer time because they will be used up within the next decades. Besides, the drastic increase in the emission of carbon dioxide into the environment, when fossil fuels (oil, gas, petrol, kerosene, etc.) are combusted in engines and automobiles has been identified as the major cause for the change of temperature in the atmosphere generally referred to as global warming.

Thus, the search for an alternative that could replace fossil fuels in the short or medium term has become imperative.

The future potential of renewable energy for the mitigation of global warming is intended to focus on six most important energy technologies viz: - bioenergy, direct solar energy, geothermal energy, hydropower, ocean energy and wind energy.

This research will mainly focused on the potential of one of these energy sources (bioenergy) taking into account its environmental, social, financial and technological benefits derivable from its clean technologies. The emphasis under this category (bioenergy) will be centered on the production of fatty acid methyl esters (FAMEs), also called biodiesel, a clean burning alternative fuel from renewable resources such as vegetable oils, animal fats and waste cooking oils. It is a nonpetroleum-based diesel fuel consisting of short chain alkyl (methyl or ethyl) esters, obtained by the

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process of transesterification of the oil (triglyceride) with primary alcohol (methanol) in the presence of a suitable catalyst (Shu et al., 2009). The biodiesel (fuel) produced from this process can be used alone or blended with conventional petro-diesel in unmodified diesel engine vehicles (Sharma et al., 2008).

The renewable sources or feedstock for biodiesel production are derived from different vegetable oils which are available as fresh plant oils such as palm oil (Elaeis guineensis), used (waste) vegetable cooking oil, palm kernel oil, coconut oil (Cocos nucifera), jatropha oil (Jatropha curcas), soybean oil (Glycine max), rape seed oil (Brassica napus), peanut oil (Arachis hypogaea), canola oil (Brassica napus), sunflower oil (Helianthus annuus) as well as animals fats with a high content in free fatty acids. In the most recent review, Europe stands out as the largest producer and user of biodiesel obtained from rapeseed (canola) oil while the United States closely followed as the second largest producer and user of biodiesel which is obtained from soybean oil or recycled restaurant grease. The type of starting feedstock for biodiesel production absolutely depends on availability and the suitability of the climate to cultivate vast hectares of land for the crop. For example, in other regions of the world (Asia for example), Malaysia, Indonesia and Thailand based their feedstock on the abundant supply of edible palm oil. India is known for the non-edible jatropha oil (Banapurmath et al., 2008).

The immediate and longtime benefits derivable from renewable energy are numerous. These include environmental benefits in which case the renewable energy technologies are from clean sources of energy and have much lower environmental impact than conventional energy technologies. On the long time basis, it will provide

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energy for our children's children because the renewable energy will not “run out”

forever. It will provide jobs and create a robust economy, and above all energy security will be guaranteed.

1.1 Transesterification process

Transesterification is the term used to describe a class of organic reactions in which an ester is transformed into another through interchange of the alkoxy moiety.

When the original ester is reacted with an alcohol, for example, transesterification process is called alcoholysis and in particular methanolysis if lowest molecular weight methanol is used. Transesterification is a reversible reaction and the tendency to attain equilibrium depends on the operating variables. The presence of excess alcohol in the reaction mixture and a catalyst (acid or base) could accelerate and control the equilibrium to achieve a high yield of the ester.

The stoichiometry of transesterification reaction requires 1 mol of a triglyceride (TG) and 3 mols of the alcohol to form di- and mono-glycerides (partial glycerides) and the final products methyl esters and glycerol. Usually, an excess of the alcohol is used to increase the yield of the methyl esters and to allow its physical separation from the glycerol formed. Investigations have shown that transesterification reaction depends on some number of parameters which enhances the product conversion.

In other words, the extent of the reaction will depend on the type of catalyst (acid or base), alcohol to vegetable oil molar ratio, temperature, purity of the reactants and free fatty acid content. Methyl esters of fatty acids are produced by

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alcoholysis (transesterification) of triglyceride with methanol in the presence of an acid or base catalyst as illustrated by the reaction Scheme 1.1. Complete conversion of the triglyceride involves three consecutive reactions with monoglyceride and diglyceride intermediates.

Scheme 1.1: 3-step reversible reactions of triglyceride where R1, R2, and R3 are long chains of carbons and hydrogen atoms (fatty acid chains) (Fukuda et al., 2001)

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Triglycerides are simple lipid and are fatty acid triesters of the trihydroxy alcohol glycerol which are present in plant and animal tissues. In particular, they are found in the food storage depots (the triglycerides in the food storage depots represent a concentrated energy source, since oxidation provides more energy than an equivalent weight of protein or carbohydrate) either as simple esters in which all the fatty acids are the same or as mixed esters in which the fatty acids are different.

Similarly, triglycerides constitute the main component of natural fats and oils. The typical molecular structure of a triglyceride is given as Scheme 1.2.

Scheme 1.2: A mole triglyceride

where R1CO2H, R2CO2H, and R3CO2H represent molecules of either the same or different fatty acids, such as butyric or caproic (short chain), palmitic or stearic (long chain), oleic, linoleic, or linolenic (unsaturated).

1.1.1 Homogeneous transesterification process

Transesterification reaction as mentioned earlier requires a suitable catalyst for the conversion of the triglyceride (vegetable oil) to fatty acid methyl esters (FAME). The use of homogeneous catalyst where the catalyst and the reactants are in same liquid-liquid phase for the production of FAME is among the various technologies that emerged over decades and has gained increased acceptability

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7

because it is widely known to give higher conversion to methyl esters but not without some shortcomings. These include free fatty acid in feedstock which formed saponified products, water in raw materials interferes with the reaction, glycerol separation is usually difficult, and purification of methyl esters require repeated washing with water which when discharged make the environment unsafe (Ma et al., 1999; Fukuda et al., 2001; Apostolakou et al., 2009).

The current industrial production of FAME basically employed homogeneous alkali-catalyzed transesterification of vegetable oils with methanol. This is because of the fast kinetics of the reaction that is involved by the use of homogeneous catalysts. For example, NaOH, KOH, (K+ or Na+)-OCH3 are most often used. It is also a known fact that, though the reaction involving these catalysts is fast, saponification (a side reaction) in the system considerably reduced FAME yield, the product requires repeated washing with water to remove glycerol. Also, in homogeneously catalyzed process, fats and alcohols are not totally miscible and vigorous mixing is required to increase the area of contact between the two immiscible phases and a kind of emulsion is produced which reduce the yield of fatty acid methyl ester (FAME) product. Moreover, the catalyst is not reusable and soap is formed. The glycerin by-product that is contaminated with the alkaline catalyst also has little market worth and disposal problem becomes aggravated. The conventional production of FAME relies on soluble sodium and potassium hydroxide catalysts; however, removal of these catalysts is technically difficult and brings extra cost to the final product.

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In the same vain, acid transesterification allows formation of ester without by-products. The main disadvantage of this process lies in the fact that the acid homogeneous transesterification involve the application of corrosive catalyst such as H2SO4, H3PO4, HNO3, and HCl. In addition, the reaction rate is generally slow.

However, at high operating temperatures and pressures, the rate and yield could be improved but this will add extra cost to the final product Macario et al., (2010). All the limitations mentioned here make the homogeneous process cumbersome and uneconomical. Thus, this makes investigation into suitable acid or basic heterogeneous catalysts, or heterogeneous catalyst with dual sites, that is, with both acid and basic functions for the process imperative.

1.1.2 Heterogeneous transesterification process

Heterogeneous catalysts (where the catalyst and the reactants are in different phase, that is, solid-liquid phase) could be employed in the transesterification process to improve the yield of fatty acid methyl ester (FAME) at lower cost. There is significant demand in energy consumption worldwide and to meet this challenge, a new and efficient catalyst for fatty acid methyl ester (FAME) production which possesses criteria such as good activity and selectivity, low cost, ease of separation and environmental friendliness is required.

Heterogeneous catalysts have been used in various processes, for example, alkali metal (Li, Na, and K) promoted alkali earth oxides (CaO, BaO, and MgO), as well as K2CO3 supported on Al2O3(K2CO3/Al2O3), has been used for transesterification of different vegetable oils (D’Cruz et al., 2007). However, there

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9

was potassium leaching into the product during the reaction and require catalyst modification to obtain higher yield and eliminate or reduce leaching.

The utilization of heterogeneous catalyst in transesterification reactions appeared very promising because they could become cheaper materials in substitution of noble metal supported on alumina, silica and other inert solids in addition to the ease of separation of the products. Heterogeneous CaO has been used in transesterification of soybean oil (Kouzu et al., 2009). Soybean and poultry fat using nano crystalline CaO (Reddy et al., 2006) have also been reported. For example, activated CaO on rapeseed oil using 0.10 g catalyst with 3.90 g methanol and 15 g oil at 60 oC in 3 h, gave 90 % and CaO pretreatment was carried out by activation with methanol at 25 oC in 1.5 h before contacting with oil (Kawashima et al., 2009).

In a similar work, Nakatani et al., (2009) reported transesterification of soybean oil over combusted oyster shell with 25 wt % catalyst, 65-70 oC in 5 h and obtained 73.8 % conversion. Mg-Al hydrotalcites was used for transesterification of rape oil at 1.5 wt % catalyst loading, alcohol to oil ratio of 6:1 and 65 oC in 4 h and the yield obtained was 90.5 % (Zeng et al., 2008). Silica-supported solid acid catalyst has also been used for the esterification of free fatty acids in sunflower oils (SO) for the production of diesel fuel (Ni and Meunier, 2007). Basic solid Mg/Zr catalysts have been applied on edible and non-edible oil with ratio Mg/Zr of 2:1 (wt/wt %), when 0.1 g catalyst was mixed with 1 g oil and 2.5 mL methanol at 65

oC for 2 h for transesterification and the results indicated over 90% methyl ester conversion.

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10 1.2 General uses and properties of biodiesel

Biodiesel, a renewable alternative fuel to diesel from fossil, will be extensively used in the near future due to its many benefits. Biodiesel can be used in the blended form-B20 (20 % of biodiesel with 80 % petroleum diesel) or in the pure form (B100) depending on the feedstock from which it is derived or the quality of the finished fuel (Sharma et al., 2008). In the blended form, it can be used in unmodified diesel engines. The flow and combustion properties of biodiesel are similar to petroleum-based diesel and thus, it can act as a substitute for diesel fuel and justify its suitability as blends with fuels. Higher blends, or even pure biodiesel (100 % biodiesel or B100), can be used in some other engines, for example as in aviation with little or no modification.

In terms of efficiency, biodiesel has positive performance attributes such as increased cetane, high fuel lubricity, and high oxygen content, which may make it a preferred blending stock with future ultra-clean diesel. It is a performance enhancer in terms of operations to conventional diesel. There is an increase in engine life span because biodiesel is more lubricating than diesel fuel. The increased lubricity will enhance engine performance and reduce the frequency of engine parts replacement.

Thus, it can serve as a replacement to sulphur (a lubricating agent) in blends. Sulphur dioxide is produced during combustion of sulphur containing diesel fuel which is a primary component in acid rain (Gerpen et al., 1997). Pure biodiesel carries about 90

% of the energy content of the normal diesel and hence it can be expected that the engine performance can be nearly the same.

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Emissions of nitrogen oxides increase with the concentration of biodiesel in the fuel and the increase is roughly 2 % for B20 (Ban-Weiss et al., 2007; Demirbas, 2007). Some biodiesel produces more nitrogen oxides than others, and some additives have shown promise in reducing the increase production of these oxides in the fuel. In the case of biodiesel, NOx emissions are a function of combustion temperature. The higher the heat of combustion the greater is the NOx emissions.

Also, because biodiesel contains more oxygen than diesel fuel, the heat of combustion is slightly higher.

Biodiesel is biodegradable and this feature makes it ideal for use in fragile areas such as natured reserves, water reserve, forestry estates, bodies of water, inland waterways and coastal waters, and in urban agglomerations. Production and use of biodiesel are environmentally friendly because of their proximity to the feedstock.

Besides, biodiesel is safe to transport because it has a high ignition temperature (higher flash point than normal diesel). No danger of explosion is associated with this fuel.

The production of biodiesel is relevant for most industrialized nations where energy demand is quite huge. For example, the demand for transport fuels is going to increase to a great extent as the world population increases. Biodiesel will enable the development and the support for sustainable society projects that are of strategic importance. Similarly, the economic and social aspects of development which aims at greater energy self-sufficiency, a more secured environment (by decreasing the air pollution from transportation and mitigating greenhouse gas emissions) and socio- economic benefits of the bottom billion will be promoted.

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The increased utilization of biodiesel will help to develop the economy and provides significant results in microeconomic growth for both the urban and rural sectors. In addition, it is hoped that the research will generate employment opportunities, thereby providing livelihood support (economic empowerment). It is expected that more plantations of oil yielding plants such as palm tree (cash crop) and others for the production of biodiesel will help to create eco-restoration and environment sanity vis-à-vis environment security and reduce drought. The long term benefits derivable from using biodiesel are improvement in national security, environmental protection, guarantees public health cum safety, and a source of income to farmers.

1.3 Problem Statement

The surge in industrialization and the unprecedented rise in world population have necessitated some few questions being asked by both developed and developing nations pertaining to human survival. The aspects of energy generation and consumption, safe environment and food are areas that have direct impact on the population. How can energy be produced from a source to meet increasing industrial demand and its consumption will p

Rujukan

DOKUMEN BERKAITAN

Figure 4.31 Response surfaces for selectivity of ETBE predicted by the model for different levels of reaction temperature and reaction time at 3 wt% catalyst loading and molar

The main parameters that affect the biodiesel yield during transesterification and esterification process are catalyst loading, methanol to oil molar ratio, reaction

Figure 4.23 shows the surface response plot for the effect of catalyst loading, methanol to oil molar ratio on the FAME yield at constant reaction temperature of 80 ˚C and 4.5

(iii) To analyse the relationship between the reaction time, temperature, catalyst loading, and oil-to-methanol molar ratio on biodiesel production using RSM.. 1.6

3) To optimize the Ceiba pentandra biodiesel production process based on three parameters setting (methanol to oil molar ratio, temperature, and reaction time) using

Furthermore, I would like to express my sincere gratitude to Professor Min Chen from the University of Oxford’s e-Research Centre for his insightful comments on

All reaction parameters (temperature, time, catalyst loading, and glycerol to acetic acid molar ratio) have been optimized to obtain the highest selectivity to

The effect of reaction time was studied using 9:1 methanol to oil ratio for cockle shell catalyst and 3:1 ratio for commercial CaO catalyst at 60°C reaction